Methods for mounting filaments in tubular incandescent lamp capsules

Abstract

A method for mounting a filament in a double ended incandescent lamp capsule. A filament assembly, including a filament, filament supports attached to each end of the filament and an external lead connected to each filament support, is located in a tubular lamp envelope. The position of the filament relative to the lamp envelope is determined, and the filament is moved to a predetermined position relative to the lamp envelope, if necessary. Then, the lamp envelope is heated sufficiently to cause the lamp envelope to deform into contact with at least one of the filament supports so as to securely anchor the filament support. The heating of the lamp envelope in regions of the filament supports can be performed simultaneously or at different times. One or both filament supports can be anchored by the tacking process.

What is claimed is: 
     
       1. A method for making a double-ended incandescent lamp capsule having an elongated lamp envelope comprising a central region, first and second seal regions in each end thereof, a first filament-support region between said first seal region and said central region, and a second filament-support region between said second seal region and said central region, said method comprising the steps of: positioning a filament assembly within said lamp envelope, said filament assembly comprising a filament and first and second filament supports attached to each end of said filament, such that said filament is within said central region of said lamp envelope, said first filament support is within said first filament-support region of said lamp envelope, and said second filament support is within said second filament-support region of said lamp envelope;   heating said first filament-support region of said lamp envelope sufficiently to cause said first filament-support region to deform into contact with said first filament support so as to securely retain said first filament support within said lamp envelope; and   sealing said lamp envelope by closing at least one of said seal regions of said lamp envelope.   
     
     
       2. A method as defined in claim 1 wherein said first and second filament-support regions are heated sufficiently to cause said first and second filament-support regions to deform into contact with said first and second filament supports, respectively, so that said first and second filament supports are securely retained within said lamp envelope. 
     
     
       3. A method as defined in claim 2 wherein said first and second filament-support regions of said lamp envelope are heated simultaneously. 
     
     
       4. A method as defined in claim 1 wherein said first filament-support region of said lamp envelope is tubular and the step of heating said first filament-support region causes the inner diameter of said filament-support region to be reduced. 
     
     
       5. A method as defined in claim 1 wherein the step of positioning said filament assembly includes the steps of determining the precise alignment of said filament relative to said lamp envelope and adjusting the alignment of said filament when necessary. 
     
     
       6. A method as defined in claim 5 wherein said filament comprises a wire coil and the step including the precise alignment of said filament assembly further includes the steps of determining the stretch of said wire coil and adjusting the spacing between successive turns of said wire coil when necessary. 
     
     
       7. A method as defined in claim 1 wherein the step of heating said first filament-support region of said lamp envelope is performed with a torch. 
     
     
       8. A method as defined in claim 1 further including the step of flushing an inert gas or a reducing gas through the lamp envelope during the step of heating said first filament-support region of said lamp envelope. 
     
     
       9. A method as defined in claim 1 further including the step of reducing the pressure within the lamp envelope to less than the pressure outside the lamp envelope during the step of heating said first filament-support region of said lamp envelope. 
     
     
       10. A method as defined in claim 1 further including the step of applying mechanical pressure to said heated first filament-support region of said lamp envelope to cause said first filament-support region of said lamp envelope to be deformed. 
     
     
       11. A method as defined in claim 1 wherein said filament assembly includes first and second lead-in wires connected to said first and second filament supports by first and second conductive foils, respectively, said method further including the step of closing said second seal region of said lamp envelope on said second lead-in wire and second conductive foil so as to anchor one end of said filament assembly in said lamp envelope prior to heating said first filament-support region of said lamp envelope. 
     
     
       12. A method as defined in claim 11 wherein the step of positioning said filament assembly includes the steps of determining the precise alignment of said filament relative to said lamp envelope and adjusting the alignment of said filament when necessary. 
     
     
       13. A method as defined in claim 12 wherein said filament comprises a wire coil and the step including the precise alignment of said filament assembly further includes the steps of determining the stretch of said wire coil and adjusting the spacing between successive coils of said wire coil when necessary.